Digital broadcasting transmitter, turbo stream processing method thereof, and digital broadcasting system having the same

ABSTRACT

A digital broadcasting transmitter, a turbo stream processing method thereof, and a digital broadcasting system having the same. The digital broadcasting transmitter includes a first compressor, forming a normal stream by compressing audio and video signals in a first compression format, a second compressor, forming a turbo stream by compressing the audio and video signals in a second compression format, a transport stream (TS) constructor, compressing the turbo stream in an H.264 format and forming the dual transfer stream by multiplexing the normal stream and the turbo stream, and a TS processor, robustly processing the dual transfer stream transmitted from the TS constructor, thus enhancing the transmission efficiency.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 11/600,033,filed on Nov. 16, 2006, which claims the benefit of Korean ApplicationNo. 2006-69389, filed Jul. 24, 2006, in the Korean Intellectual PropertyOffice and also claims the benefit under 35 U.S.C. §119(a) of U.S.Provisional Application No. 60/752,410, filed in the United StatesPatents and Trademark Office on Dec. 22, 2005, the disclosures of whichare incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

An aspect of the present invention relates to a digital broadcastingtransmitter, a turbo stream processing method thereof, and a digitalbroadcasting system having the same. More particularly, an aspect of thepresent invention relates to a digital broadcasting transmitter whichprocesses a normal stream and a turbo stream compressed in differentformats from each other, a turbo stream processing method thereof, and adigital broadcasting system having the same.

2. Description of the Related Art

There are different digital broadcasting standards such as aU.S.-oriented advanced television system committee (ATSC) format and aEuropean-oriented digital video broadcasting-handheld (DVB-H).

The U.S.-oriented transmission format is based on the NationalTelevision System Committee (NTSC) frequency band, and has the advantageof easily implementing a transmitter and receiver. The U.S.-orientedtransmission format is a single carrier wave amplitude modulationvestigial side band (VSB) format, that is, this format can transmithigh-quality video, audio and auxiliary data in the single 6 MHzbandwidth.

In the U.S.-oriented transmission format, an image signal is compressedin a moving picture experts group-2 (MPEG-2), a sound and voice signalis compressed in digital audio compression (AC-3), and the VSBtechnology is used to transmit such signals.

The reason why the image signal and the sound and voice signals arecompressed in the MPEG-2 and AC-3, respectively is to reduce the bitrate of the image, voice and digital auxiliary data stream.

In the U.S.-oriented transmission format, the MPEG-2 used to compress animage signal has been developed for instances when a channel bandwidthor a storage capacity of a storing medium are limited, and whenefficient transmission structure is needed. The MPEG-2 is a compressionformat which is interoperably designed with the asynchronous transfermode (ATM) transmission structure.

Conventionally, only normal streams are used, but recently a dualtransport stream adding a turbo stream with enhanced coding to thenormal stream is used.

In this case, the compression performance and image quality of the turbostream which is compressed in the conventional MPEG-2, is considerablydecreased. Accordingly, the load on a transmission system and operatingexpenses of a broadcasting station are increased.

SUMMARY OF THE INVENTION

An aspect of embodiments of the present invention is to solve at leastthe above and/or other problems and/or disadvantages and to provide theadvantages described below and/or other advantages. Accordingly, anaspect of embodiments of the present invention is to provide a digitalbroadcasting transmitter to enhance the compression performance andimage quality by compressing a normal stream and a turbo stream of adual transport stream in different formats, a turbo stream processingmethod thereof, and a digital broadcasting system having the same.

Accordingly, an aspect of the present invention provides a digitalbroadcasting transmitter, including a first compressor, forming a normalstream by compressing audio and video signals in a first compressionformat; a second compressor, forming a turbo stream by compressing theaudio and video signals in a second compression format; a transportstream (TS) constructor, compressing the turbo stream in an H.264 formatand forming the dual transfer stream by multiplexing the normal streamand the turbo stream; and a TS processor, robustly processing the dualtransfer stream transmitted from the TS constructor.

According to another aspect of the present invention, the firstcompression format may include an MPEG-2 (Moving Picture ExpertsGroup-2) format, and the second compression format may include an H.264format.

According to another aspect of the present invention, the TS constructormay include an RS, encoder RS-encoding the compressed turbo stream; aplace holder maker, adding a region to insert a parity to the RS-encodedturbo stream; an interleaver, interleaving the turbo stream with theregion to insert the parity; and a TS multiplexer (MUX), multiplexingthe interleaved turbo stream and the normal stream.

According to another aspect of the present invention, there is provideda turbo stream processing method of a digital broadcasting transmitter,including forming a normal stream by compressing audio and video signalsin a first compression format; forming a turbo stream by compressing theaudio and video signals in a second compression format; forming a dualtransfer stream by multiplexing a normal stream and the turbo stream;and robustly processing the dual transfer stream.

According to another aspect of the present invention, the firstcompression format may include an MPEG-2 (Moving Picture ExpertsGroup-2) format, and the second compression format may include an H.264format.

According to another aspect of the present invention, the forming of thedual transfer stream may include RS-encoding the compressed turbostream; adding a region to insert a parity to the RS-encoded turbostream; interleaving the turbo stream added with the region to insertthe parity; and multiplexing the interleaved turbo stream and the normalstream.

According to another aspect of the present invention, there is provideda digital broadcasting system, including a transmitter, forming a dualtransfer stream by multiplexing a normal stream of a first compressionformat and a turbo stream of a second compression format,robust-processing the dual transfer stream and outputting therobust-processed dual transfer stream; and a receiver, receiving thedual transfer stream and recovering the normal stream and the turbostream.

According to another aspect of the present invention, the firstcompression format may include an MPEG-2 (Moving Picture ExpertsGroup-2) format, and the second compression format may include an H.264format.

According to another aspect of the present invention, the transmittermay include a first compressor forming the normal stream by compressingaudio and video signals in the first compression format; a secondcompressor forming the turbo stream by compressing the audio and videosignals in the second compression format; a TS constructor forming adual transfer stream by multiplexing the normal stream and the turbostream; and a TS processor robust-processing the dual transfer streamreceived from the TS constructor.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will becomeapparent and more readily appreciated from the following description ofthe embodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a block diagram describing a digital broadcasting transmitteraccording to an embodiment of the present invention;

FIG. 2 is a block diagram describing the TS constructor of FIG. 1;

FIGS. 3A through 3D are views describing an H.264 packet constructed inthe TS constructor of FIG. 2;

FIG. 4 is a flow chart describing a turbo stream processing method of adigital broadcasting transmitter according to an embodiment of thepresent invention; and

FIG. 5 is a block diagram of a digital broadcasting receiver accordingto an embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. The embodiments are described below in order to explain thepresent invention by referring to the figures.

FIG. 1 is a block diagram describing a digital broadcasting transmitteraccording to an embodiment of the present invention.

Referring to FIG. 1, the digital broadcasting transmitter 1000 accordingto an embodiment of the present invention includes a transport stream(TS) constructor 100 and a TS processor 200.

The TS constructor 100 compresses a turbo stream in the H.264 format,and multiplexes a normal stream and the turbo stream to construct a dualtransport stream. The TS constructor 100 will be described in detail inFIG. 2.

The TS processor 200 robustly processes and transmits the dual transportstream transmitted from the TS constructor 100 to the receiver. The TSprocessor 200 includes a randomizer 201, a Reed-Solomon (RS) encoder203, a data interleaver 205, a turbo processor 207, a trellis encoder209, a multiplexer (MUX) 211, a pilot inserter 213, a modulator 215, anda radio frequency (RF) converter 217.

The randomizer 201 randomizes a dual transfer stream to make the bestuse of an allocated channel space.

The RS encoder 203 RS-encodes the dual transfer stream randomized by therandomizer 201. The RS encoder 203 may be a concatenated coder whichadds a parity to the transfer stream to correct errors caused by channelfeatures upon transmission.

The data interleaver 205 interleaves the dual transfer stream RS-encodedby the RS encoder 203. Data-interleaving does not alter data, butchanges the location of frame in the frame of data.

In this embodiment, the data interleaver 205 is located between the RSencoder 203 and the turbo processor 207, but is not necessarily limitedto this location. For example, the data interleaver 205 can be locatedbetween the turbo processor 207 and the trellis encoder 209.

The turbo processor 207 robustly processes the dual transfer streaminterleaved by the data interleaver 205. More specifically, the turboprocessor 207 separates the dual transfer stream into the normal streamand the turbo stream, passes the normal stream, turbo-codes the turbostream, and multiplexes and outputs the normal stream and theturbo-coded turbo stream.

The trellis encoder 209 trellis-encodes the dual transfer streamrobustly processed in the turbo processor 207. The trellis encoder 209converts the dual transfer stream into a symbol, and performssymbol-mapping through trellis-encoding of certain rates.

The MUX 211 multiplexes the dual transfer stream by adding a segmentsync and a field sync to the dual transfer stream trellis-encoded by thetrellis encoder 209.

The pilot inserter 213 adds a pilot signal to the dual transfer streamincluding the field sync and the segment sync added by the MUX 211. Thepilot signal occurs at a zero frequency point of a spectrum where alittle bit of DC deviation is supplied to the 8-VSB baseband rightbefore modulation and a little bit of residual carrier waves aremodulated, and functions to synchronize an RF phase locked loop (PLL)circuit of the receiver regardless of the transfer signal.

The modulator 215 performs pulse-shaping for the transfer stream addedwith the pilot signal by the pilot inserter 213, loads the transferstream into an intermediate frequency carrier wave, and performs VSBmodulation to modulate the amplitude.

The RF converter 217 RF-converts and amplifies the transfer streamVSB-modulated by the modulator 215, and transmits the transfer streamthrough a channel allocated to a certain band.

FIG. 2 is a block diagram describing the first and the secondcompressors, and the TS constructor.

Referring to FIG. 2, there are first and second compressors 10 and 20provided at a front end of the TS constructor 100, and the TSconstructor 100 includes an RS encoder 120, a place holder maker 130, aninterleaver 140, and a TS MUX 150.

The first compressor 10 forms a normal stream by compressing audiosignals and video signals according to a first compression format, andthe normal stream is inputted to the TS constructor 100. The firstcompression format may preferably be in an MPEG-2 (Moving PictureExperts Group-2) format.

The second compressor 20 forms a turbo stream by compressing the audiosignals and video signals according to a second compression format, andthe turbo stream is inputted to the TS constructor 100. The secondcompression format may preferably be in an H.264 format.

The H.264 format is known as the advanced video coding, is a standardfor coded expression of visual information, and emphasizes efficiencyand reliability. Additionally, the H.264 format compresses approximatelytwice (about 50%) more efficient than the MPEG-2 format, and isapproximately 1.5 times (about 35%) more efficient than the MPEG-4format. Upon real-time compression such as broadcasting, the performancedifference somewhat decreases, but is 30-40% more efficient than theMPEG-2 format.

For example, to implement the SD-level image quality, data has to betransmitted at the bit rate (the transmission rate of a digital signal)of 4 Mbps (4 million bits per second) in the MPEG-2 format, but 2 Mbps,which is half of the above bit rate, is enough in the H.264 format.

Good compression efficiency means less damage in the image quality inspite of the high compression rate. If the compression rate increases,the capacity decreases. Accordingly, if the compression performance isgood higher resolution can be implemented when transmitted through adigital signal of less capacity.

In addition, if higher resolution can be implemented with less capacity,a frequency corresponding to the transmission route is less used.Therefore, in limited frequency resources, since the H.264 format cantransmit using less capacity in the same frequency band, extra room iscreated in the frequency. Accordingly, if the H.264 format is used, morechannel services are possible.

The RS encoder 120 adds and encodes the parity to the turbo streamcompressed in the H.264 format by the second compressor 20.

The place holder maker 130 generates a region to insert a parity to theturbo stream, which will be added in the turbo processor 207 of the TSprocessor 200. For example, 1 byte of 8 bits, which is the constructionunit of a turbo stream, is formed as 1 byte of 4 bits, so that 2 bytesare generated.

The interleaver 140 interleaves the turbo stream with the region forinserting the parity. The interleaver 140 can be omitted if necessary,or can be replaced with a different element. However, if the RS encoder120 is included in the TS constructor 100, the interleaver 140 may beincluded in the TS constructor 100.

The TS MUX 150 constructs a dual transfer stream by multiplexing thenormal stream input in the TS constructor 100, and the turbo streaminterleaved in the interleaver 140, and outputs the dual transferstream.

FIGS. 3A through 3D are views describing an H.264 packet constructed inthe TS constructor of FIG. 2.

In general, a packet applied to the digital broadcasting consists of 1byte of sync, 3 bytes of header, and 184 bytes of payload. The header ofthe packet includes a packet identifier (PID). A normal stream and arobust stream are separated according to a type of data included in thepayload.

FIG. 3A exemplifies a turbo stream input to the TS constructor 100,including the turbo data in the payload part. That is, the turbo data,compressed in H.264 format by the second compressor 20, is input to theRS encoder 120, the place holder maker 130, the interleaver 140 and theTS MUX 150 of the TS constructor 100.

FIG. 3B exemplifies a normal stream input to the TS constructor 100, andthe normal data is included in the payload part, and also includes anadaptation field to insert the turbo data considering connection to theturbo stream. The adaptation field includes 2 bytes of an AF header andan N byte of null data.

The turbo stream in FIG. 3A and the normal stream in FIG. 3B aremultiplexed in the TS MUX 150 to form a dual transfer stream as in FIG.3C.

FIG. 3D shows a different connection form of a turbo stream and a normalstream, a packet entirely includes a turbo stream or a normal stream.The TS MUX 140 arranges a turbo stream and a normal stream in the ratioof 1:3. The embodiment of arranging a turbo stream and a normal streamin the ratio of 1:3 is exemplified, but it is not limited to thisembodiment.

The dual transfer streams in FIGS. 3A through 3D are similar to a dualtransfer stream compressed in the conventional MPEG-2 format, butdifferent in that the turbo stream compressed by H.264 format has ahigher efficiency that the normal stream.

FIG. 4 is a flow chart describing a turbo stream processing method of adigital broadcasting transmitter according to an embodiment of thepresent invention.

Referring to FIGS. 1-4, the turbo stream processing method of thedigital broadcasting transmitter according to an embodiment of thepresent invention will be described.

The first compressor 10 forms a normal stream by compressing audio andvideo signals according to a first compression format (S300), and thesecond compressor 20 constructs a turbo stream by compressing audio andvideo signal according to a second compression format (S310).

The turbo stream compressed by the second compressor 20 is RS-encoded bybeing added with a parity by the RS encoder 120 (S310), and the placeholder maker 130 generates a region to be added with a parity in the TSprocessor 200 (S320).

The turbo stream with a region to be added with a parity is interleavedby the interleaver 140 (S330), and is input to the TS MUX 150. The TSMUX 150 multiplexes the normal stream and the turbo stream to form adual transfer stream (S340).

Next, the dual transfer stream is input to the TS processor 200, passesrandomization, RS encoding, interleaving, turbo coding, trellisencoding, multiplexing, pilot insertion, VSB modulation, and RFconversion, and is transmitted through a channel.

FIG. 5 is a block diagram of a digital broadcasting receiver accordingto an embodiment of the present invention.

Referring to FIG. 5, the digital broadcasting receiver 2000 includes ademodulator 410, an equalizer 420, a first processor 430 and a secondprocessor 440.

The demodulator 410 detects synchronization of a synchronous signalappended to a baseband signal of the dual TS received from the digitalbroadcasting transmitter 1000, and accordingly performs demodulation ofthe dual TS.

The equalizer 420 equalizes the demodulated dual TS, and compensates fora multi-path channel distortion. The dual TS, when equalized by theequalizer 420, is then provided to the first and second processors 430and 440.

The first processor 430 processes the normal stream of the dual TS, andthus recovers the normal stream. The first processor 430 includes aviterbi decoder 431, a first deinterleaver 432, an RS decoder 433 and afirst derandomizer 434.

The viterbi decoder 431 performs error correction of the normal streamof the equalized dual TS, decodes the error-corrected symbol, andoutputs the decoded normal stream packet.

The first deinterleaver 432 deinterleaves the decoded normal streampacket to rearrange the distributed packets.

The RS decoder 433 RS-decodes the deinterleaved normal stream packet tocorrect errors.

The first derandomizer 434 derandomizes the RS-decoded normal streampacket to recover the normal stream data.

Meanwhile, the second processor 440 processes the turbo stream of thedual TS to recover the turbo stream data. With reference to FIG. 5, thesecond processor 440 includes a turbo decoder 441, a seconddeinterleaver 442, a parity eliminator 443, a second derandomizer 444, aturbo de-MUX 445, and an eraser decoder 446.

The turbo decoder 441 performs turbo decoding of the turbo stream of theequalized dual TS. The turbo decoder 441 inserts the turbo stream backinto the dual TS to reconstruct the dual TS when the turbo decoding iscompleted.

The second deinterleaver 442 deinterleaves the reconstructed dual TS torearrange the packets.

The parity eliminator 443 removes parities from the deinterleaved dualTS.

The second derandomizer 444 derandomizes the parity-removed dual TS.

The turbo de-MUX 445 demultiplexes the derandomized dual TS to recoverturbo stream data.

The eraser decoder 446 performs eraser decoding with the recovered turbostream data.

The transmitter 1000 performs eraser encoding to remove noise, and theninserts the turbo stream to the normal stream to form a dual TS.Therefore, as the eraser decoder 446 of the receiver 2000 performseraser decoding on the eraser-encoded turbo stream of the transmitter1000, noise of the turbo stream can be removed and reception improved.

FIG. 5 only exemplifies a digital broadcasting receiver 2000 accordingto an embodiment of the present invention, and therefore is not limitedto this example only. Therefore, many alternatives, modifications, andvariations may be adequately made. For example, the second processor 440may include the turbo decoder 441 only, while the first processor 430 ismade to process the normal stream and the turbo stream, respectively.

As can be appreciated from the above description of a digitalbroadcasting transmitter, a turbo stream processing method thereof, anda digital broadcasting system having the same according to an embodimentof the present invention, the normal stream is processed in MPEG-2format and the turbo stream is compressed in the H.264 format, making itmore efficient to use the turbo stream in the present A-VSB system.

Therefore, the following benefits can be attained from the above systemand method, broadcasting of similar image quality can be implemented ata lower transmission rate, broadcasting of a better image quality ispossible at the same rate as the transmission rate of the MPEG-2 format,and broadcasting of the similar image quality can be implemented invarious channels. Accordingly, operating expenses of a broadcastingstation can be reduced and profits maximized.

Although a few embodiments of the present invention have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in this embodiment without departing from theprinciples and spirit of the invention, the scope of which

1. A digital broadcast transmitter, comprising: a first compressor tooutput a normal data stream compressed by a Moving Picture ExpertsGroup-2 (MPEG-2) format; a second compressor to output an additionaldata stream compressed by an H.264 format; a place holder maker toinsert a placeholder for parity into the additional data stream; and atransport stream (TS) constructor to multiplex the normal data streamand the additional data stream to construct a TS; wherein the additionaldata stream is processed robustly, wherein the additional data stream isfirst interleaved before being multiplexed with the normal data streamand second interleaved after being multiplexed with the normal datastream, wherein the normal data stream and the additional data streamare arranged in a predetermined ratio by the multiplexing.
 2. Thedigital broadcasting transmitter of claim 1, wherein further comprises:a Reed-Solomon (RS) encoder to RS-encode the additional data stream. 3.The digital broadcast transmitter of claim 1, wherein the normal datastream comprises video data and the additional data stream comprisesvideo data.
 4. The digital broadcast transmitter of claim 1, wherein thenormal data stream comprises video data and audio data.
 5. The digitalbroadcast transmitter of claim 1, wherein the additional data streamcomprises video data and audio data.
 6. A stream processing method of adigital broadcasting transmitter, comprising: outputting a normal datastream compressed by a Moving Picture Experts Group-2 (MPEG-2) format;outputting an additional data stream compressed by an H.264 format;inserting a placeholder for parity into the additional data stream; andmultiplexing the normal data stream and the additional data stream toconstruct a transport stream (TS), wherein the additional data stream isprocessed robustly, wherein the additional data stream is firstinterleaved before being multiplexed with the normal data stream andsecond interleaved after being multiplexed with the normal data stream,wherein the normal data stream and the additional data stream arearranged in a predetermined ratio by the multiplexing.
 7. The streamprocessing method of claim 6, wherein the multiplexing and constructingof the TS comprises: Reed-Solomon (RS)-encoding the additional datastream.